不同光谱区间日光照射下水体成分的光致羟基自由基生成研究  

Generation of hydroxyl radical from water constituents under different spectra bands of sunlight

作　　者：王静[1] 邢梦林 邰超[1] 赵同谦[1] 阴永光[3] 

机构地区：[1]河南理工大学资源环境学院,焦作454000 [2]河南省环境监测中心,郑州450004 [3]环境化学与生态毒理学国家重点实验室,中国科学院生态环境研究中心,北京100085

出　　处：《环境化学》2015年第12期2162-2169,共8页Environmental Chemistry

基　　金：国家自然科学基金(41371501,21377156);河南理工大学杰出青年(HPUJ2013-04)资助

摘　　要：本文对硝酸根、亚硝酸根、过氧化氢和可溶性有机质(Dissolved organic matter,DOM)等4种水体成分在不同波段的太阳光照射下羟基自由基的光化学生成情况进行了研究.结果表明,硝酸根、亚硝酸根和过氧化氢三者的光致羟基自由基生成速率(vs.光通量)与其浓度之间有良好的线性关系,说明三者的光致羟基自由基生成是三者直接光解产生羟基自由基,都为一级反应,单位浓度(mol·L^(-1))的硝酸根、亚硝酸根、过氧化氢的羟基自由基生成速率分别为13.6、2.11×10~3、2.90×10~2μmol·L^(-1)·E^(-1)·m^2;DOM的光化学过程可以产生羟基自由基,但羟基自由基生成速率与DOM浓度间不存在明显的线性关系,具体的原因可能是DOM光致羟基自由基生成可经由非过氧化氢途径(途径1,DOM直接光解)和过氧化氢途径(途径2,过氧化氢光解)两种途径生成,而高浓度DOM的存在会产生较强的滤光作用,同时也会阻断途径2中过氧化氢的生成,降低羟基自由基的生成速率;不同光谱区间的日光对4种成分的羟基自由基贡献不同,可见光区对4种组分贡献均远小于紫外区,紫外区UVA和UVB对硝酸根和过氧化氢的羟基自由基光化学生成贡献较为接近,UVA和UVB对亚硝酸根和DOM的羟基自由基光化学生成贡献存在明显差异,差异的产生由水体成分对太阳光谱的吸收性质和太阳光谱能量分布共同决定.In this paper,hydroxyl radical generations from nitrate,nitrite,hydrogen peroxide and dissolved organic matter（ DOM） under sunlight of different spectra bands were investigated. It was found that there were good linear relationships between the hydroxyl radical generation rate（ vs.PAR） and the concentration of nitrate, nitrite and hydrogen peroxide. The hydroxyl radical generation rates per molar concentration of nitrate,nitrite and hydrogen peroxide were 13.6,2.11 ×10~3and 2. 90 × 10~2μmol·L^（-1）·E^（-1）·m^2,respectively. No apparent linear relationship was found between the hydroxyl radical generation rate and the dissolved organic matter concentration,whichindicated more complexity of the hydroxyl radical generation from DOM than nitrate,nitrite and hydrogen peroxide. Hydroxyl radial could be photo-generated from DOM by two ways： hydrogen peroxide independent pathway（ pathway 1） and hydrogen peroxide dependent pathway（ pathway 2）.DOM with relatively high concentrations would produce light attenuation effect,and at the same time inhibit production of hydrogen peroxide in pathway 2,and decrease of rate of hydroxyl radical generation. The contribution of interaction between dissolved organic matter and other water constituents for the generation of hydroxyl peroxide needs further research. Great differences were found between the influences of the sunlight spectral band on the hydroxyl radical generation from nitrate,nitrite,hydrogen peroxide and dissolved organic matter,which was thought to be a result of different absorption of the water constituents and the spectral energy distribution of sunlight.

关 键 词：羟基自由基 光化学 水体成分 太阳光 光谱区间 

分 类 号：X131.2[环境科学与工程—环境科学]